Today's telecommunication networks have to provide enhanced switching and service provision functionalities requiring the mapping of address information according to the network numbering plan of the telecommunication network towards service access codes and/or network element addresses.
For example, number portability in a telecommunication network permits a user to retain their telephone number whenever the end-user changes from one telecommunication service provider domain to another telecommunication service provider domain.
The provisioning of a number of portability service for mobile subscribers is, for example, described in U.S. 2002/0114440 A1. The telecommunication network includes a set of service provider domains. Some of these domains are mobile telecommunication domains serving mobile stations. At least some of the areas served by these domains can be, and likely are, geographically coextensive. Further, some of the domains serve fixed stations. Fixed station domains include at least one local exchange that is connected with a plurality of fixed subscriber stations. Mobile telecommunication domains each have respective gateway nodes each of which take the form of gateway mobile switching center (GMSC). Further, mobile telecommunication domains each include respective data bases connected to and maintained by service management systems, respectively. These data bases are subscriber location servers including information which facilitates number portability for many types of subscribers in their respective domains, including mobile subscribers.
Typically, a hashing algorithm is used to search number portability data bases as it is normally used in commercially available data bases.
Further, U.S. Pat. No. 6,625,273 B1 describes the provisioning of a local number portability service within a public switched telecommunication network based on the SS7 protocol.
In case of local number portability, standard calls like toll-free calls, calling-cut-calls and other such calls require additional data in order to be routed by the signaling transfer points (STPs). The transaction capabilities application part (TCAP) functionality defined in the SS7 protocol is used to obtain the additional routing information required to complete these calls. TCAP messages are exchanged between SSPs and SCPs (=Service Control Point) for a variety of queries. For such call, the SCPs are responsible for call routing data. To improve this system, an additional system is installed between the service providers SSP and the network that acts as local cache storing the results of SCP queries. When subsequent requests for the same lookup are received, the query is intercepted, a lookup is performed and the locally stored number is sent back to the SSP. Then the SSP has the information necessary to complete the call. The query results are stored in the local cache with a defined expiration time. After the result expires from the cache, the subsequent request for the lookup will be executed in the standard fashion, that means retrieving the information from the SCP and repopulating the local cache.
According to this concept, a cache memory having a list of translation information is searched to provide number portability.